/*
 * Copyright (c) 2011-2014 Pivotal Software, Inc.
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *         http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */

package org.camunda.bpm.extension.reactor.projectreactor.timer;

import org.camunda.bpm.extension.reactor.projectreactor.support.ReactorFatalException;

import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicLong;
import java.util.function.Consumer;

/**
 * @author Jon Brisbin
 */
public abstract class TimeUtils {

  private static final int DEFAULT_RESOLUTION = 100;
  private static final AtomicLong now = new AtomicLong();
  private static Timer timer;

  protected TimeUtils() {
  }

  public static long approxCurrentTimeMillis() {
    getTimer();
    return now.get();
  }

  public static void setTimer(Timer timer) {
    timer.schedule(new Consumer<Long>() {
      @Override
      public void accept(Long aLong) {
        now.set(System.currentTimeMillis());
      }
    }, DEFAULT_RESOLUTION, TimeUnit.MILLISECONDS, DEFAULT_RESOLUTION);
    now.set(System.currentTimeMillis());
    TimeUtils.timer = timer;
  }

  public static Timer getTimer() {
    if (null == timer) {
      setTimer(new HashWheelTimer(DEFAULT_RESOLUTION));
    }
    return timer;
  }

  public static void checkResolution(long time, long resolution) {
    if (time % resolution != 0) {
      throw ReactorFatalException.create(new IllegalArgumentException(
        "Period must be a multiple of Timer resolution (e.g. period % resolution == 0 ). " +
          "Resolution for this Timer is: " + resolution + "ms"
      ));
    }
  }

}
